QEMU, increase graphics memory

Question

I need to get more graphics memory on my QEMU Windows client.

I decided to install Virtio drivers for QEMU to achieve that purpose.

I create an imagine_file like this:

qemu-img create -f raw image_file 4G

Also, I ran the windows-install like this:

qemu-system-x86_64 -enable-kvm -m 4G -cdrom "OS.iso" -boot order=c -drive file=image_file,if=virtio

But when Windows ran, it didn't find any hard-drive (the image_file basically). It asked for some drivers instead. I think it wanted drivers to communicate with the hard-drive (image_file).

Running the install without Virtio works though:

qemu-system-x86_64 -enable-kvm -m 4G -cdrom "OS.iso" -boot order=d -drive file=image_file,format=raw

The difference betweeen the two commands is:

order=c vs order=d

and

if=virtio vs format=raw

How do I install windows with Virtio in QEMU?

My original goal is to get 512 MB of graphics memory on Windows (running as a guest in QEMU). Unfortunately, by default (no Virtio) I get 8MB of video memory which is not enough for my purposes

Thanks

P.S. My OS is Arch-Linux

Solution

You need to add a device to your VM. For example, if you decided to use VGA adapter (mode), your code should look like this:

qemu-system-x86_64 -enable-kvm -m 4G -cdrom "OS.iso" -boot order=c -drive file=image_file,if=virtio -device VGA,vgamem_mb=256

You can get the list of the devices that is possible to add to the VM by running the following command (print a list of QEMU supported devices by category):

qemu-system-x86_64 -device help

Additionally, the options per device can be determined by running:

qemu-system-x86_64 -device device_name,help

For the example with VGA adapter:

qemu-system-z86_64 -device VGA,help

Here is a similar post: How to set video memory with KVM/QEMU virtualization?